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Systems Engineering. Mike Pryzby Swales Aerospace August 16-17, 2005. LRO Systems Team. LRO Systems Engineering Implementation Approach.

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Systems engineering

Systems Engineering

Mike Pryzby

Swales Aerospace

August 16-17, 2005



Lro systems engineering implementation approach
LRO Systems Engineering Implementation Approach

  • SE is integrated into project as defined in our SEMP in accordance with GPR 7120.5 and tailored to reflect the successful approach taken by the core LRO team on past missions

  • Key SE documents include; SEMP, Golden Rules, MRD & Siblings including Electrical, Mechanical, Thermal, and Pointing specifications, Allocations and Con Ops documents

  • Gold used by subsystems as requirements at L2/L3. Compliance matrix in process, due at PDR

  • SE activities defined by phase in our SEMP, phase A&B presented today

  • Evidence of our SE process is the content of this SRR


Preliminary Analysis - Phase A

Understanding the Objectives

- Understand and define Level 1 science requirements; Identify full and minimum mission reqs

- 1st draft of Level 1 reqs for review at MDR

- Validate Level 1 requirement and show flowdown to Level 2 requirements at MD

Operations Concept Development

- Identify and define LRO Mission Phases

- Complete preliminary draft version of LRO Operation Concept Document

Architecture & Design Development

- Review LRO ORDT Report & previous concept studies

- Identify key LRO design drivers & perform trade studies of various implementation design concepts

- Define architecture design concept and balance with reqs and ops concept

Requirements Identification & Management

- Define draft Level 2 MRD reqs & demonstrate flowdown & traceability to Level 1 reqs at MDR

- Detailed walkthrough of MRD Level 2 reqs traceability and assignment at SRR

- Initial entry of MRD Level 2 reqs into DOORS database for mgmt and tracking

- Define initial LRO Doc Tree, detailing subsystem reqs documentation structure & responsibility

Validation & Verification

- Perform initial trade studies and fold into initial system architecture design concept

- Demonstrate MRD Level 2 reqs traceability to Level 1 reqs and to implementation design concept at SRR

Interfaces & ICDs

- Begin initial discussions across instrument and subsystem lines on interface design concepts as part of initial architecture design baseline effort

- Identify proposed ICD documents within LRO Document Tree

Mission Environments

- Complete initial radiation environment assessment and document in draft radiation white paper

- Distribute contamination questionnaire to Instr, establish contamination working group, and complete draft contamination assessment

- Define initial flight operational & test environments in Systems Verif & Envi Def document

Technical Resource Budget Tracking

- Establish formulation resource allocations as part of architecture design concept investigations

- Baseline resource allocations at end of Phase A within SCR allocation margins

- Bring resource allocations under CM at beginning of Phase B

Risk Management

- Establish Risk Management Plan & Procedures & identify, classify, & report initial risk items

- Begin initial fault tree analysis and reliability block diagrams and use to optimize design concept

System Milestone Reviews

- Hold Mission Design Retreat (MDR) to review Level 1 reqs and initial design concept

- Hold System Reqs retreat (SRR) for detailed walkthrough of Level 2 MRD reqs and demonstrate flowdown & traceability to Level 1 reqs

- Hold SRR/SCR for external review team- acts as review milestone for progression Phase B

Configuration Management & Documentation

- Define LRO document tree and define subject, when due, and who responsible for each document

System Engineering Management Plan

- Complete draft SEMP and plans for Phase A definition of “single system design” concept

- Update SEMP for Phase B activity plans to “design the right system”

Phase A Plans and ActivitiesLRO SEMP (431-PLAN-000005) System Engineering Lifecycle Activities MatrixAll Completed 


System Definition - Phase B

Understanding the Objectives

- Level 1 Science Reqs competed & signed off by NASA HQ; Includes minimum mission reqs

- Track any changes to Level 1 reqs (changes req NASA HQ approval)

- Refine LRO Mission Phases definitions and LRO Operation Concept Document

Operations Concept Development 

Architecture & Design Development ◘

- CM block diagram of LRO architecture design concept - Begin preliminary system and subsystem design process

- Begin conceptual breadboard design process; use breadboards as testbeds and for interface testing across ss for risk reduction

Requirements Identification & Management

- Define draft Level 2 MRD reqs & demonstrate flowdown & traceability to Level 1 reqs at MDR

- Detailed walkthrough of MRD Level 2 reqs traceability and assignment at SRR

- Initial entry of MRD Level 2 reqs into DOORS database for mgmt and tracking

- Define initial LRO Doc Tree, detailing subsystem reqs documentation structure & responsibility

Validation & Verification ◘

- Update MRD Level 2 reqs with verification information and use process to check validity of reqs

Interfaces & ICDs

- Baseline and release initial documents and ICDs on LRO Document Tree

Mission Environments◘

- Update contamination assessment and complete draft Contamination Control Plan

- Begin evaluation and tracking of parts and materials for use in identified flight environment

- Update flight operational & test environments in Systems Verif & Envi Def document

Technical Resource Budget Tracking

- Bring resource allocations under CM at beginning of Phase B within appropriate margins

- Track and control resource allocations to complete Phase B within PDR margin allocations

Risk Management ◘

- Complete initial FMEA of preliminary design concept and fold results back into design

- Update fault tree analysis and reliability block diagrams & use to further optimize design concept

- Ongoing identification, classification, & reporting of risk items per Risk Mgmt Plan & Procedures

System Milestone Reviews ◘

- Hold subsystem peer reviews and PDRs to review Level 3 reqs and initial design concepts

- Hold Mission PDR for external review team- acts as review milestone for progression Phase C

Configuration Management & Documentation

- Initiate CCB process to address changes to configured documents

- Bring Level 1 Reqs, MRD Level 2 Reqs, and Level 3 Subsystem spec under CM

System Engineering Management Plan ◘

- Update SEMP for Phase C Design activity plans to ensure system is “implemented right”

Phase B Plans and Activities LRO SEMP (431-PLAN-000005) System Engineering Lifecycle Activities Matrix Black –done, ◘Green – In progress



Review process
Review Process

???

  • Peer Reviews discipline driven, ingrained as an institutional process at GSFC and our PI institutions

  • Project mandated peer reviews by SE and management as deemed necessary

    • Examples include; FPGA’s, LROC Optical Design, PDE Architecture

  • Peer Review Process in accordance with GPR 8700.6A and LRO Peer Review Plan.

    • SE attends and assigns actions as warranted

    • Project mandated/schedules as necessary, part of GSFC process across all project elements

    • Team comprised of technical experts, internal and external as required

    • Desire to keep review team through project lifecycle

    • Contested RFAs tracked in Project Action Item database

  • PDR, CDR, PER, PSR etc content defined in our SE plan and controlled by LRO IIRT Review Plan (431-PLAN-000007)


Validation and verification
Validation and Verification

  • Validation process includes use of DOORS to insure no orphan requirements and proper traceability and flow down

  • Verification is part our CM process and a mandatory section of each requirements document

  • Verification matrix using DOORS database will include the following fields

    • Ownership to identify which individual is responsible for verifying this requirement, as well as those others with a significant effort in the verification activities.

    • Verification method; Inspection / Analysis / Demonstration / Test

    • Description of type of test, if needed

    • Verification Documentation to show where the requirement is verified

    • Verification Result Summary

  • Mission Verification Plan will define overall process and plan for completion.


Risk management intertwines with mission success reliability to minimize risk

Safety

Req.

Level 2

Req.

Level 3

Req.

Mission

Success

Criteria

Advanced

Functional

Schematics

(concept)

Advanced

Functional

Schematics

(concept)

Degraded

Mission

Criteria

Identify Mission

Success &

Degraded

Mission

Performance

Identify Mission

Success &

Degraded

Mission

Performance

Risks

Risks

Trades

Trades

Req.

Chg

Req.

Chg

Risk Management Intertwines with Mission Success & Reliability to Minimize Risk

  • Mission Success Engineering, Reliability Engineering, and Risk Management coordinating an integrated process

    • Capture spacecraft concept/design using Advanced Functional Schematic (AFS)

    • Identify Mission Success and Degraded Mission performance of spacecraft concept.

      • Criticality & Degraded Mode Analyses

      • Critical Items List, FMEAs, RBDs, FTAs, & PRA

      • Safety & Reliability Analyses

    • Mission Success vs. Implementation Decisions

      • Risks to Mission Success assessed

      • Trades Space (Requirements vs. Implementation Considerations)

      • Recommend changes to level 2, 3 and 4 requirements that improve mission success

  • Risk inputs provided to Systems Engineering & Project Management


Architecture optimization from single string to selective redundancy
Architecture Optimization from Single String to Selective Redundancy

  • Mission Success requirements flow top down to individual subsystems/elements

  • Advanced Functional Schematics (AFS) capture big picture; end to end view of spacecraft systems and architecture.

  • Spacecraft operations, mission modes & phases, timing, event durations and criticality considered.

  • Criticality of risk factors to mission success and residual risks considered

  • Apportionment of requirements to improve mission success

    • Hardware Requirements, Independence, Fault Tolerance, Reliability Apportionment



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